Monitoring apparatus and communication system

Abstract

A monitoring apparatus capable of efficiently disabling, when an invalid frame is detected in an in-vehicle network, the invalid frame by a simple method, for example, includes a reception unit configured to receive a frame from a communication network, a determination unit configured to determine whether the frame received by the reception unit is a valid frame or an invalid frame which is not a valid frame, and a transmission unit configured to transmit, if the determination unit determines that the received frame is an invalid frame, a frame including information identical to that included in the valid frame.

What is claimed is: 
     
         1 . A monitoring apparatus for monitoring a frame transmitted/received via a communication network, comprising:
 a reception unit configured to receive the frame from the communication network;   a determination unit configured to determine whether the frame received by the reception unit is a valid frame or an invalid frame which is not a valid frame; and   a transmission unit configured to transmit, if the determination unit determines that the received frame is an invalid frame, a frame including information identical to that included in the valid frame.   
     
     
         2 . The monitoring apparatus according to  claim 1 , wherein the monitoring apparatus is incorporated in a control apparatus connected to the communication network. 
     
     
         3 . The monitoring apparatus according to  claim 2 , wherein the monitoring apparatus and the control apparatus are connected by internal communication different from the communication network,
 the monitoring apparatus further includes a memory which receives a valid frame, which the control apparatus holds as a valid frame of a valid transmission source, from the control apparatus via the internal communication, and stores the valid frame, and   the determination unit compares the valid frame stored in the memory with the frame received by the reception unit, and determines, based on a result of the comparison, whether the received frame is a valid frame or an invalid frame.   
     
     
         4 . The monitoring apparatus according to  claim 2 , wherein the determination unit checks whether reception time of the frame received by the reception unit has a predetermined period, and determines, as an invalid frame, a frame received at a period other than the predetermined period. 
     
     
         5 . The monitoring apparatus according to  claim 1 , wherein the monitoring apparatus is connected to the communication network independently of a control apparatus, connected to the communication network, for transmitting/receiving a frame, and receives a frame from the control apparatus via the communication network. 
     
     
         6 . The monitoring apparatus according to  claim 5 , wherein the determination unit checks whether reception time of a frame received by the reception unit has a predetermined period, and determines, as an invalid frame, a frame received at a period other than the predetermined period. 
     
     
         7 . The monitoring apparatus according to  claim 1 , wherein the communication network is an in-vehicle network for transmitting/receiving a frame complying with a standard of a CAN bus, and
 the frame contains a transmission source ID indicating a transmission source of the frame, and control information.   
     
     
         8 . The monitoring apparatus according to  claim 7 , wherein a control apparatus on a reception side of the frame, which is connected to the communication network, includes a reception buffer,
 the reception buffer sequentially stores received frames, and   the control apparatus on the reception side reads out a latest received frame among the frames stored in the reception buffer, from the reception buffer, and executes control based on control information contained in the latest received frame.   
     
     
         9 . The monitoring apparatus according to  claim 8 , wherein the transmission unit transmits a frame including information identical to that included in the valid frame after the control apparatus on the reception side receives the invalid frame and before the control apparatus on the reception side reads out the invalid frame as the latest received frame. 
     
     
         10 . A communication system comprising:
 a plurality of control apparatuses, each integrating a monitoring apparatus, and transmitting/receiving a frame via a communication path, wherein the monitoring apparatus monitors the frame transmitted/received via the communication network from a network, and comprises:   a reception unit configured to receive the frame from the communication network;   a determination unit configured to determine whether the frame received by the reception unit is a valid frame or an invalid frame which is not a valid frame; and   a transmission unit configured to transmit, if the determination unit determines that the received frame is an invalid frame, a frame including information identical to that included in the valid frame.   
     
     
         11 . A communication system comprising:
 a monitoring apparatus configured to be connected to a communication path; and   a control apparatus configured to transmit/receive a frame via the communication path,   wherein the monitoring apparatus monitors a frame transmitted/received via the communication path from a communication network, and comprises:   a reception unit configured to receive the frame from the communication network;   a determination unit configured to determine whether the frame received by the reception unit is a valid frame or an invalid frame which is not a valid frame; and   a transmission unit configured to transmit, if the determination unit determines that the received frame is an invalid frame, a frame including information identical to that included in the valid frame.